Electric drills are usually constructed as straight-drilling machines in which the drill spindle extends parallel to the motor shaft and axis of the housing and, for specific purposes, as angular-drilling machines in which the drill spindle is aligned at a right angle to the motor shaft and housing axis. In certain applications in which both straight and angular drilling must be carried out, as is the case in installations in wooden house construction, the two machines must be at hand for continuous alternation.
The use of a tool receptacle head serving as special accessory for a conventional drill to eliminate the need for two drills is known. By way of example, DE 36 34 734 A1 discloses a drill that includes two separate housing parts which are located opposite one another to define a hollow space and which are guided along a diagonally extending dividing plane. One housing part carries a support for a drive shaft and the other housing part carries a support for a power take-off shaft which projects out of the tool receptacle head and carries a drill chuck. The drive shaft and power take-off shaft are connected with one another by a double cardan or universal joint so as to be rigid with respect to torsion relative to one another. One hollow-cylindrical housing part of the tool receptacle head is placed on the spindle neck of the drill and the drill spindle of the drill is coupled with a driver by means of a double edge. The driver sits on the drive shaft so as to be fixed with respect to rotation relative to it. In the basic position of the two housing parts, the axes of the drive and power take-off shafts are flush with one another. Due to the relative rotation of the two housing parts, the power take-off shaft can be aligned in such a way that its axis encloses an acute or right angle with the axis of the drive shaft.
A standard drill can be re-tooled with this known tool receptacle head so as to form an angle drill which can also perform straight drilling. While such a separate tool receptacle head serving as attachment may be suited to the requirements of some hobbyists, it is not acceptable for professional machines.
U.S. Pat. No. 5,533,581 discloses a drill suitable for professional use that includes a drill with a housing, an electric motor which is received in the housing, a motor shaft parallel to the housing axis, and a work spindle which is driven by the electric motor via a transmission gearing. The housing is divided along a dividing plane for the purpose of switching from straight drilling to angular drilling and it is provided that the front housing part containing a bearing for the work spindle and the rear housing part containing the electric motor can swivel relative to one another in such a way that the work spindle projecting out of the front housing part can occupy any angle between 0 degrees and 90 degrees or more relative to the motor shaft. A catch lock which can be unlocked and/or locked manually stops the two housing parts in the selected swivel position. A torsionally rigid transmission of force from the motor shaft to the work spindle is realized in every swivel position of the housing parts in the transmission gearing.
While the prior art drills are useful, they have various limitations. For example, drills are frequently exposed to impacts, both intentional and accidental, on the bits which are held by the drills. The prior art drills generally transmit these impact forces through the gearing mechanisms which allow for the relative positioning of the work spindle with respect to the motor shaft. Accordingly, the gears must be designed to absorb the impact forces. Such gears may increase the weight of the drill and increase the size of the forward section of the drill. Increased weight increases the fatigue experienced by a user, particularly users who use the tool infrequently. Moreover, the additional bulk of the drill reduces the usefulness of the tool in confined areas.
Additionally, the locking mechanisms used to restrict articulation in prior articulating drill systems may be difficult to use or susceptible to accidental activation. Furthermore, in certain known devices the articulating gear mechanism is exposed allowing contaminants into the mechanism as well as presenting a safety concern as clothing or appendages may be caught by revolving gears.
What is needed is an articulating power hand tool which protects internal components from damage resulting from axial impact. It would be beneficial to further protect the internal components from contamination and reduce the potential for external items becoming entrapped by the internal components.
What is further needed is an articulating power hand tool with a reduced forward section and a compact articulating system to allow for use of the tool in confined areas.
What is also needed is an articulating power hand tool having a latch mechanism exhibiting increased strength and which further reduces the potential of accidental manipulation.